Starting and operating circuits for fluorescent lamps



1955 w. s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Filed June 30 1950 2 Sheets-Sheet l FIG. 3

INVENTOR. William S.H.Homi|fon BY HIS ATTORNEYS Aug. 2, 1955 STARTING AND Filed June 50 950 w. s. H. HAMILTON 2,714,690 OPERATING CIRCUITS FOR FLUORESCENT LAMPS 2 Sheets-Sheet 2 INVENTOR. William S.H. Homil'ron WM zuwma, 7M2; RMQ

HIS ATTORNEYS United States Patent Ofifice Z,7l4,69fi Patented Aug. 2, 1955 TARTENG AND UPERATING CIRCUITS FOR FLUQRESCENT LAMPS William S. H. Hamilton, Larchrnont, N. Y. Application June 3%), 1950, Serial No. 171,495 4 Claims. (Cl. 315-403) This invention relates to improvements in starting and operating circuits for fluorescent lamps, and particularly to fluorescent lamps of the types which are diflicult to start and which require an inductive kick to start them into operation when they are sufiiciently preheated to fire.

The object of the invention is to provide circuit arrangements embodying novel starting and controlling means adapted to give an efiective inductive kick to start the lamp when it is otherwise ready to fire, and which overcomes functional defects of some of the starters in general use in the way of ensuring greater reliability in action and a more readily and rapid starting of the lamp, without repeated starter actions, if the lamp is in good order and free from mechanical or electrical defects.

In the accompanying drawings I have shown in Figs. 1 to 4 inclusive, diagrammatic views of circuit arrangements for D. C. and A. C. lamps embodying my invention, which are adapted to give an effective inductive kick for a starting action, all of which also show a glow in one or more filaments as soon as the circuit is closed, and all of which also designed to quickly restart after they have been in use and it is desired to restart them without the usual restarting delays.

Figs. and 6 are views showing a snap action type of starter which may be desiredly used in the circuits, the views showing the closed and open positions of a normally closed starter and corresponding positions ot-a coacting relay switch.

Referring now more particularly to Fig. l of the drawings, it designates a gas containing fluorescent lamp envelope having spaced negative and positive electrodes 2 and 3, the electrodeZ being of filamentary type while the electrode 3 is short-circuited. One end-of the negative electrode 2 is connected by a'lead conductor 4to the negative terminal 5 of a D. C. line, while the other end of said electrode is connected to a conductor 6 forming part of a primary preheating circuit and having arranged therein current limitingresistances 7 and 8, the heating resistance 9 of a thermostatic starter-19, and the automatically closing switch member ll'of a starting and operating relay 12. One end of the electrode 3 is connected through an operating conductor, having input and output portions or branches 13 and 13", to the positive terminal 14 of the line. The said portions 13, 13" areconnected at a common junction point to the input conductor 15' of a normally open secondary preheating and control circuit. Such circuit includes the conductors 13 and 15' and an output conductor 16, connectedat its output end to the conductor 6 between the resistances 7 and 8.

The proximate ends of the conductors 15' and 16 are separated by a gap adapted to be bridged by engagement of the contacts 17 and 18 of the normally open thermostatic starter lti. A condenser 19 is placed across the contacts l718 to prevent arcing when said contacts open. The relay 12 includes a bypass connection 20 disposed between the input ends of the conductors 6 and 13', which is normally closed by the switch 11, and a relay coil 21.

A condenser 12 is placed across the contacts of switch 11 to prevent arcing when said contacts open.

The coil 21 is disposed in the conductor 13' between the reactor 23 and the conductor branch 13", so as to be cut out of the path of flow of preheating current in the primary preheating circuit, and arranged to be normally de-energized when the switch member 11 is closed. Also, coil 21 is so arranged as to be energized when the lamp fires under line voltage, or when the thermostatic switch contacts 1718 close to retract the switch 11, which breaks the preheating circuit 6. A reactor coil 23 is arranged in the conductor branch 13 ahead of the relay coil and operates to give an inductive kick to start the lamp when the contacts 17-l8 open after having been closed, if the lamp, after being heated, does not fire directly under line voltage applied to the filament 3 through the conductor 13. A ballast lamp 22 of proper current limiting value is arranged in the conductor'13".

In starting, current flows from the line through connection 29, the normally closed self-closing relay switch 11, and through the heater 9 and resistances 7 and 8 in conductor 6 to the filament 2 and back to the line, thus heating the filament 2. If the lamp then does not start on line voltage before the thermostatic switch contacts 17-48 close, on the closing of these contacts the relay will pick up and open the switch 11 and the secondary preheating circuit will be established from the line through conductors 13, 15', 16' and resistance 8 to continue the preheating of the filament 2.

When the contacts 1718 of the thermostatic switch open, an inductive kick will be generated by opening the circuit through the reactor coil 23 sufiicient to fire the lamp. When the lamp fires the relay coil 21 will be energized through conductors 13 and 13" and ballast lamp 22, opening the primary preheating circuit of condoctor 6 and preventing further action on the part of thermostatic switch it). This circuit arrangement permits starting of a hard starting lamp without preheating the electrode 3 and gives satisfactory results with certain types of lamps of this character.

Fig. 2 shows a circuit arrangement which is suitable for use with either an A. C. or D. C. source of current device 10. The operation of this circuit arrangement will be readily understood in the light of the foregoing description applying to the operation of the circuit atrangement shown in Fig. 1.

Fig. 3 shows a circuit arrangement in which a'preheating and operating conductor 130 leading from terminal 14'- is normally connected by a self-closing .relay switch arranged therein with a preheating conductor section 6d which is normally connected by the normally closed contacts iii-J3 of the thermostatic swich It) with a conductor 62 containing the heater element 9 and cur rent limiting resistance 8b and leading to the negative filament 2 of the lamp 1.

The relay coil 21!) is arranged between a conductor 20b and an operating conductor section 13:! leading to the positive filament 3 of the lamp, which is sh'ort-circuited. in the lead between the terminal 14 and the switch 110 is disposed the primary of a reactor-transformer 2311, whose secondary is disposed in the circuit to the positive filament of the lamp, comprising the relay coil 21:), ballast lamp 22, and conductors 20b and 13d. The secondary of the reactor-transformer is adapted to amplify the inductive kick generated by the opening or" the primary winding of reactor transformer 23a when thermostatic switch contacts 1718 open, and this amplified inductive kick applied through the circuit to the positive filament of the lamp through conductors 2% and 13d will cause the lamp to fire and energize relay coil 21b, causing contacts 110 to reverse themselves from the position shown and to cut off the supply of preheating current through conductors 6d and 6e as well as short-circuiting the secondary winding of the reactor-transformer as soon as the lamp fires.

This arrangement provides a means for starting a lamp by impressing a higher voltage on it than can be obtained by breaking the circuit through a simple reactor. The use of such means has been found very desirable and efficient in starting certain long lamps as well as certain types of hard starting lamps. By use of the arrangement shown current flows through a reactor-transformer having its secondary disposed in such manner as to supplement the inductive kick obtained when the circuit through the preheating circuit is broken.

In the operation of this circuit, preheating current flows through the primary winding of the reactor-transformer 23a, the upper set of contacts 110 of the relay, the normally closed contacts 17-18 of the thermostatic switch 10, the heater element 9, and resistance 8b, to the filament 2 and thence to the negative side of the line. A circuit 201) is also established from the lower side of the primary winding of the reactor-transformer through its secondary winding, the relay coil 21b and the ballast lamp 22 to the short-circuited positive filament 3 of the lamp. The characteristic of the lamp being such that it will not fire without a heavy inductive kick being given to it, the negative filament 2 glows, but the lamp does not fire until the heater element 9 has heated the thermostatic switch for a sufficient length of time to cause its contacts JUL-18 to open.

When these contacts open they cause an inductive kick or voltage surge through the primary winding of the reactor-transformer 23a, which is amplified by the secondary winding and the total value is sufiicient to fire the lamp through the circuit from the secondary winding, the relay coil 21b, the ballast lamp 22 and the positive filament 3 of the lamp. When this takes place, the relay picks up and reverses its contacts, breaking the circuit to the thermostatic switch it? and resistance 81), and short-circuiting the secondary of the reactortransformer. This arrangement prevails as long as the lamp continues to burn, allowing the thermostatic switch time to cool off and reclose its contacts 17-18 so as to be ready for another start.

If, when the lamp is operating, the line circuit is broken at any time, the relay reverses to the normal position shown in Fig. 3, ready to initiate a restarting action as soon as the line circuit is again closed. By using the relay to short circuit the secondary winding of the reactor-transformer, as soon as the lamp has fired, the secondary winding can be made of a relatively large number of turns of small wire that will give a large supplementary boost to the inductive kick obtained by breaking the primary of the reactor-transformer, while at the same time keeping the secondary winding out of the circuit during the operation of the lamp, which is of advantage, as a low resistance and higher current carrying capacity are desired than would be obtained if the secondary winding were allowed to remain in the circuit with the lamp burning. This permits the reactor-transformer to be made smaller than would otherwise be the case.

it is to be understood that in the circuit organiza tions shown in Figs. 1, 3 and 4 the positive filament may be short-circuited or left open-circuited depending on the characteristics of the particular circuits.

Pig. 4 shows a circuit arrangement for use with a direct current supply somewhat similar to that of Fig. 3 and in which a simple reactor coil 230 is used in place of a In the operation of the circuit lamp used in the reactor-transformer.

its contacts back 17-48, under the same fixed bimetallic disk which shown in Fig. 4 current flows from the positive line terminal 14 through conductor 13]- containing the reactor coil 230 through normally closed automatically reclosing relay switch 112, conductor 6g, the normally closed contacts 1'7-18 of thermostatic switch 1h, heater 9 of thermostatic switch 10, conductor 6h and resistance 8c t0 and through the lamp filament 2 and through conductor 4 to negative line terminal 5, thus establishing a preheating circuit to heat the filament 2. A branch circuit is also established from the low side of the reactor through relay coil 21d, ballast lamp 22 and conductor 13g, to the positive filament 3 of the fluorescent lamp.

When current is applied to the preheating circuit it heats up the heater element 9 and filament 2 and when the thermostatic switch 10 is heated sufficiently to cause the contacts 17-l8 to open, these contacts on opening break the preheating circuit and cause the reactor 23c to give an inductive kick to start the lamp. This inductive kick is applied through the branch circuit containing the relay coil 21d and ballast lamp 22 to the positive filament 3 of the fluorescent lamp, whereby the fluorescent lamp is caused to fire. As soon as the lamp fires, the relay coil is energized and opens the switch 11a which prevents the preheating circuit from being reestablished through the resistance 80 and negative filament 2 when the contacts 17-18 of the thermostatic switch reclose upon cooling. While contacts 17-48 are prevented at this time from closing the preheating circuit, they are in position to reclose the same and immediately restart the lamp if the line current is cut off to deenergize the relay coil and allow switch file to close. Then through re-application of line voltage the above described starting cycle will be repeated.

This circuit has the advantage over the ordinary type of circuit in which a thermostatic starter is used to maintain the running connections of the lamp in that in such a circuit, the thermostatic switch cannot immediately reclose upon removal of line voltage and hence there is a starting delay if the line circuit is opened and then almost immediately reclosed. During this time no current flows through the negative filament because the thermostatic switch contacts are open, and hence it is impossible to tell whether the circuit is completed or not, whereas, with the circuit arrangement shown in Fig. 4, contacts conditions, will immediately supply preheating current to the lamp when the line circuit is opened and then shortly reclosed. The subject matter of Fig. 4 is being claimed in applicants copending application, Serial No. 144,345, filed February 15, 1950.

Preferably the circuit arrangements herein shown employ thermostatic starters of the quick-snap-switch type in which a pivoted switch member proper is connected by an insulated stem to a concave-convex peripherally is adapted to bow from one position to another in its opening and closing actions nd which, according to the structural arrangement of a parts, may be either a normally open or a normally closed switch, as shown in the circuit arrangements herein disclosed.

A switch of this type is shown as used as a normally closed switch in some of the circuits herein disclosed.

As shown in Fig. 5, the switch has a fixed contact or pivoted switch member 18 which is connected by an insulated stem 15a to a bimetallic actuating disk of the character described arranged to be heated by the heater 9. Fig. 5 shows the switch member 18 in closed position and a coacting relay switch 11:: is in its related closed position. When heated the disk 18!), which is normally bowed in one direction, is bowed in the opposite direction as shown in Fig. 6, whereby switch member 18 is opened. Fig. 6 shows the related position of the coacting relay switch lie when the thermostatic switch contacts 17-1S are opened. The arrangement is in accordance with that shown in Fig. 4, but the thermostatic switch may be employed as a normally closed switch in other equivalent circuits or as a normally open switch by reversing the action of its parts in an obvious manner. It will be understood that after contacts 1718 open, as shown in full lines in Fig. 6, and cause switch 11e to be opened to break the preheating circuit, contacts 1718 upon cooling will return to closed position, as shown in dotted lines in Fig. 6, while switch 11:; remains open as long as the lamp is operating.

All the circuits herein disclosed provide reliable, rugged and efiicient starting and operating means for long and contacts, ducing firing temperature electrode heating, said circuit extending from one side of a voltage source to the oppobe preheated, said primary winding, said normally closed relay switch contacts, said delay rupt the preheating circuit and maintain said circuit open during the operation of the discharge device.

2. In combination,

a gaseous electric discharge device having two electrodes,

including in series connection said electrode to be preheated, said primary winding, said normally closed relay switch contacts, a current limiting device, said delay device operating circuit and said delay device contacts, the

References Cited in the file of this patent UNITED STATES PATENTS 1,984,489 Mutsaers Dec. 18, 1934 2,046,980 Van Wijk July 7, 1936 2,266,616 Hall 2- Dec. 16, 1941 2,291,355 Scott July 28, 1942 2,305,385 Hall Dec. 15, 1942 2,341,520 Babb Feb. 15, 1944 2,438,557 Hehenkamp Mar. 30, 1948 2,465,059 Campbell Mar. 22, 1949 FOREIGN PATENTS 530,828 Great Britain Dec. 23, 1940 

